Spa shell



FIG. 1 is a top front perspective of a spa shell showing our new design, the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is a top plan view of the spa shell of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2; and,

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 2;

The bottom is plain and unornamented. 

We claim the ornamental design for a spa shell, as shown and described. 